BEIJING, July 8, 2009 (AFP) -  Police killed 400 Uighurs in the capital of China's Xinjiang region during ethnic unrest there, exiled Uighur leader Rebiya Kadeer wrote in Wednesday's Wall Street Journal Asia.

Kadeer said Uighur sources within "East Turkestan", the separatist name for the northwest region, had told her 400 Uighurs had died "as a result of police shootings and beatings" in Urumqi since violence erupted there on Sunday.    

The president of the World Uighur Congress said that unrest was spreading across the region and that unconfirmed reports also indicated more than 100 Uighurs had been killed in Kashgar, another major city in Xinjiang.

Chinese authorities have said 156 people died in Sunday's violence in Urumqi. They have not made clear how many of the victims were Han Chinese and how many were Uighur, or how they died.

China has blamed Kadeer for instigating the violence, which she strongly denies.

In the Wall Street Journal Asia, Kadeer expressed concerns about the security sweep that Chinese authorities have said has already led to the arrests of 1,434 suspects.

"Uighurs have contacted me to report that the Chinese authorities are in the process of conducting a house-to-house search of Uighur homes and are arresting male Uighurs," she wrote.

"They say that Uighurs are afraid to walk the streets in the capital of their homeland."

Sunday's protest by Muslim Uighurs were linked to a brawl between Uighurs and Han Chinese workers at a toy factory in southern China last month, which left two Uighurs dead.

Kadeer said the protest against the authorities' response to the initial incident was peaceful and should not have descended into violence.

"I unequivocally condemn the use of violence by Uighurs during the demonstration as much as I do China's use of excessive force against protestors," she wrote.

The 62-year-old Kadeer spent six years in prison in China before being deported in March 2005 to join her family in the United States.

The former millionaire businesswoman was once among the wealthiest people in China and enjoyed the trust of the Chinese authorities.

Beijing now denounces her as a terrorist and separatist.